21437564132021 has 2 divisors, whose sum is σ = 21437564132022. Its totient is φ = 21437564132020.

The previous prime is 21437564131979. The next prime is 21437564132057. The reversal of 21437564132021 is 12023146573412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16342210502500 + 5095353629521 = 4042550^2 + 2257289^2 .

It is a cyclic number.

It is not a de Polignac number, because 21437564132021 - 2⁶ = 21437564131957 is a prime.

It is a super-2 number, since 2×21437564132021² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21437564132021.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21437564132921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10718782066010 + 10718782066011.

It is an arithmetic number, because the mean of its divisors is an integer number (10718782066011).

Almost surely, 2^{21437564132021} is an apocalyptic number.

It is an amenable number.

21437564132021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21437564132021 is an equidigital number, since it uses as much as digits as its factorization.

21437564132021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 241920, while the sum is 41.

The spelling of 21437564132021 in words is "twenty-one trillion, four hundred thirty-seven billion, five hundred sixty-four million, one hundred thirty-two thousand, twenty-one".